I don’t think banks are the ones against Bitcoin. It should be the government that is against Bitcoin because they don’t have control over it. The banks actually report to the government and because Bitcoin isn’t doing the same, they don’t like it. Because starting from tax and other things they’d have implemented or rule they’d have set, they can’t. Bitcoin takes out the middle man and the government can’t do nothing about it, no matter much they dislike it.
Banks may not be directly against Bitcoin but they are surely indirectly against Bitcoin because they are directly working with the government and they review and reveal every information that is requested from the government by them since they are always scared of the politicians who are in government working with them to launder money here and there. The government has never been in support of the invention of cryptocurrency because it is transparent and the informations are private and users are usually in control of their funds and transactions unlike banks where the funds of the citizens and their transactions are controlled by banks and can be traced by the government whwn they need, banks csn not support Bitcoin because they see Bitcoin as a threat to the existing fiat and people may likely stop visiting the bank if bitcoin transactions is accepted for payment of goods and services all over the world.